title: Single-photon-level quantum image memory based on cold atomic ensembles.
abstract: A quantum memory is a key component for quantum networks, which will enable the distribution of quantum information. Its successful development requires storage of single-photon light. Encoding photons with spatial shape through higher-dimensional states significantly increases their information-carrying capability and network capacity. However, constructing such quantum memories is challenging. Here we report the first experimental realization of a true single-photon-carrying orbital angular momentum stored via electromagnetically induced transparency in a cold atomic ensemble. Our experiments show that the non-classical pair correlation between trigger photon and retrieved photon is retained, and the spatial structure of input and retrieved photons exhibits strong similarity. More importantly, we demonstrate that single-photon coherence is preserved during storage. The ability to store spatial structure at the single-photon level opens the possibility for high-dimensional quantum memories.
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Ding
authors.forename: Zhi-Yuan
authors.initials: ZY
authors.lastname: Zhou
authors.forename: Bao-Sen
authors.initials: BS
authors.lastname: Shi
authors.forename: Guang-Can
authors.initials: GC
authors.lastname: Guo